Bent pushrod!!! Help please!!

[commercialcobb]

I didn't do the engine only the car. I have had a tapping sound from the driverside bank for a while now and finally decided to do a valve adjustment. When removing the valve cover screws, they were so loose (explains oil leak on top of the header) that it took ZERO effort or less to unscrew them. Was not impressed at that point!! Pulled the valve cover and I found (Pic #1) something I wasnt expecting!! I have had smoke and OIL splattering up from the collector from that cylinders exhaust pipe that has been filling the engine compartment and cockpit. I now realize I have been running on 7 cylinders for some time and it was the intake cylinder that had the bent pushrod. I am assuming that is somewhat good because at least any pressure in the cylinder was realesed through the exhaust as opposed to combustion being strangled inside the cylider bore! Now under close examination I have found little damage to the the roller/rocker.

I have several questions if you would please help me???

1. What type of damage have I done getting smoke from that cylinder that wasn't getting fuel??
Is that oil getting sucked in through the intake valve via vacuum opening the intake valve and burning inside the exhaust header??

2. Why did that rod come loose?
Poor adjustment or not properly locked by the set screw??

3. (Photo #5) Why are my pushrods (most of them) getting chaffed by the rod guides up to .06in??
Wrong valve guides or adjustments are wrong allowing the rods to chaff on the guides???

4. Do I need to pull the intake and check the lifter for damage??
Has the lifter and/or cam been damaged by the lifter coming down whenever it wants and getting smacked by the cam??

4. What do I need to do next?
Please help me, I have spent WAY too much money on this motor to loose it now!!!!!!!!

Thanks for any and all help!!! I am sorry about the photos, they are from my phone....

Thank you, Thank you, Thank you!!!!!

[commercialcobb]

Also I have adjusted the carb and timing with this problem and cylinder not firing, does that all need to be re-done?? I thought it was just a minor valve adjustment so I didn't yank off the valve cover for some time after I heard the tapping. Probably 80 miles ago under haul ass driving.. STUPID ME!!!!

[Tom Wells]

commercialcobb,

I need to offer a "disqualify" pill, as this is a bit outside what I know. What follows is guesswork...

I've seen stock 460s cough up a pushrod by bending it. Replace the pushrod and go usually works. These engines have stock rocker geometry and hydraulic lifters.

Your engine has aftermarket rockers and hardened pushrod guides. You don't say whether the cam is solid or hydraulic.

In either case, the pushrod length is critical. Also, the pushrods need to be hard enough to be compatible with the guides. Stock parts won't work. Likewise the placement of the hardened guide plates is critical. On my engine the plates had to be split and tack welded to get proper alignment.

Bottom line: you need someone who knows custom pushrod/rocker/guide plate assembly to look at your setup and advise you.

Tom

[Rick Parker]

You must get hardened pushrods. Looks like one or more of the guide plates is damaged too. Get some qualified help. Best advice I can suggest.

Good luck

[commercialcobb]

From Summit Racing's website, are you guys talking about the "Cold-Forged 4130 Chromoly" pushrods?? They have several types of Hardened steel, forged steel and Chromoly. I am assuming the Chromoly is the one's your talking about or is there rods somewhere else that I have not seen?? Give me some more direction please.

[Rick Parker]

Contact Comp Cams direct. Ask for their recommendation. Be sure to tell them you have guide plates. Are your rocker studs screw in or press fit at this time? You need this info.

[bobcowan]

hard to tell from the pictures. But it appears that the fracture occurred where the push rod contacts the guide plate. The straight push rod looks like it has a smaller diameter in that same area. That means the original builder made a big mistake, and used stock push rods instead of hardened. once the rod wears, it creates a weak spot, and simple spring pressure will cause it to bend.

This should not be that big of a deal for you. Go to summit and buy some hardened push rods for your engine. The diameter depends on spring pressures. If you're using a mild hydraulic roller cam, with matching "light" springs, then a stock diameter rod will be fine. But if you have higher spring pressures for a "bigger" cam, then get the heavy walled Magnums, with an increased diameter.

Bigger is not always better. Bigger rods are heavier, and the increased mass can cause valve float unless you also increase the spring pressures to control it. Unless you're running it to the redline, it's probably not that big of a deal, though.

Repalce all 16 rods. Otherwise the same thing will happen to all of them eventually.

Finding the proper rod length is not that difficult. Take a look at the wear patterns on the valve tips. If they're wearing in the center of the valve tip, then the geometry is perfect. If the wear pattern is off center, you'll need to evaluate the geomtry and see what needs to be changed. Lots of info on that here and elsewhere on the web. IIRC, Comp Cams has a good tech article on that.

[CarsByCarl]

Yup, looks like somebody installed non-hardened pushrods and they're all getting chewed up.

If it were my engine, I'd pull the intake and visually inspect the lifter and the cam lobe. It should be fine, but better safe than sorry. If you find the lifter laying in the valley, you may have issues with the bearings due to loss of oil pressure.

For what it's worth, I had a customer who bought a shortblock from me use pushrods from a well respected manufacturer that were supposed to be hardened, and they all got chewed up like yours inside thirty minutes.

[Keithc8]

Like mentioned above it appears that they used non hardened pushrods, they wore and then it bent. You will have to replace the pushrods and then run through the valves and set them. You would want to change the oil and filter as well as this metal would have gotten into the oil.
I think that doing this will solve your problems and then you could re-adjust the carb as needed.

Good luck, Keith

[Gaz64]

Originally Posted by commercialcobb

I didn't do the engine only the car. I have had a tapping sound from the driverside bank for a while now and finally decided to do a valve adjustment. When removing the valve cover screws, they were so loose (explains oil leak on top of the header) that it took ZERO effort or less to unscrew them. Was not impressed at that point!! Pulled the valve cover and I found (Pic #1) something I wasnt expecting!! I have had smoke and OIL splattering up from the collector from that cylinders exhaust pipe that has been filling the engine compartment and cockpit. I now realize I have been running on 7 cylinders for some time and it was the intake cylinder that had the bent pushrod. I am assuming that is somewhat good because at least any pressure in the cylinder was realesed through the exhaust as opposed to combustion being strangled inside the cylider bore! Now under close examination I have found little damage to the the roller/rocker.

I have several questions if you would please help me???

1. What type of damage have I done getting smoke from that cylinder that wasn't getting fuel??
Is that oil getting sucked in through the intake valve via vacuum opening the intake valve and burning inside the exhaust header??

2. Why did that rod come loose?
Poor adjustment or not properly locked by the set screw??

3. (Photo #5) Why are my pushrods (most of them) getting chaffed by the rod guides up to .06in??
Wrong valve guides or adjustments are wrong allowing the rods to chaff on the guides???

4. Do I need to pull the intake and check the lifter for damage??
Has the lifter and/or cam been damaged by the lifter coming down whenever it wants and getting smacked by the cam??

5. What do I need to do next?
Please help me, I have spent WAY too much money on this motor to loose it now!!!!!!!!

Thanks for any and all help!!! I am sorry about the photos, they are from my phone....

Thank you, Thank you, Thank you!!!!!

1. The oil was pulled into the cylinder past the rings while the piston was descending on the intake stroke. Vacuum in the cylinder with no intake valve operation causes this.

4. You should inspect the base of the offending lifter and the respective cam lobe, more than likely some form of non-uniform wear.

[mreid]

Replace all 16 pushrods with the correct length hardened version, adjust the valves, replace the spark plug in the affected cylinder, change the oil/filter, and readjust the carb. I think you will be fine.

[CHANMADD]

Chances are good that the lifter jumped out of its bore . A new motor requires tightening of valve covers and exhaust header bolts amongst others for the first few miles. Matching components is paramount.